Help me in solving FIND_X problem

help
,
1

My issue

what is the problem here?

My code

#include <iostream>
using namespace std;

int main() {
	int t;
	cin>>t;
	while(t--){
	int a,b,c,d;
	cin>>a>>b>>c>>d;
	int x=1;
	while((a+x)%b!=(c+x)%d){
	    x++;
	}
	cout<<x<<endl;
	}
	return 0;
}

Problem Link: FIND_X Problem - CodeChef

2

@viga
brute force will not work for this problem .
plzz refer the following solution for better understand of optimal solution

#include <iostream>
#include<bits/stdc++.h>
#define ll long long
using namespace std;
int main() {
	// your code goes herei
	int t;
	cin>>t;
	while(t--)
	{
	    ll a,b,c,d;
	    cin>>a>>b>>c>>d;
	    ll r1,r2;
	    r1=a%b;r2=c%d;
	    ll d1=b-r1,d2=d-r2;
	    if(d1>1 && d2>1)
	    {
	        cout<<"1"<<endl;
	    }
	    else if(d1==d2)
	    {
	        cout<<"1"<<endl;
	    }
	    else
	    {
	       // ll i=1,m1=min(b,d);
	       //// a++;c++;
	       // while(1)
	       // {
	       //     if((a+i)%b==(c+i)%d)
	       //     {
	       //         cout<<i<<endl;
	       //         break;
	       //     }
	       //     else
	       //     {
	       //         i++;
	       //     }
	       // }
	        ll g1=__gcd(b,d);
	        ll l1=(b*d)/g1;
	        cout<<(l1-r1)<<endl;
	    }
	}
	return 0;
}